Electric water heater



F. W. MOFFAT.

ELECTRIC WATER HEATER.

APPLICATION FILED APR. 2?, [9214 40 994 7 Patented Feb. 21, 1922.

INVENTUR.

FREDERICK W. HOFFAT, OF WESTON. ONTARIO, CANADA.

ELECTRIC WATER HEATER.

Specification of Letters Patent.

Patented Feb. 21,1922.

application he April 27, 1921. Serial No. 4mm.

To all whom it may concern:

Be it known that I, F nnonnrox W. Morra'r, of the town of lVeston, in the county of York, Province of Ontario, Canada, a subject of the King of Great Britain, have invented, certain new and useful Improve ments in Electric Water Heaters, of which the following is a specification.

This invention relates to apparatus adaptedfor the heating of water for household orv other purposes and particularly to the t pe of apparatus disclosed in my prior nited' States Patent 1,320,890 dated Nov. 4th"- 1919.

The common arrangement of making the cylindrical resistance wire support with helical grooves formed therein, in which the wirwalre wound, is very hard, to make correctly as these supports have to be die cast, further this type of support necessitates a shell of insulating material to prevent a broken resistance wire causing a short circuit, and my object is to devise a support for a heatingelement that may be easily formed by. dies and having integral means for preventing a broken resistance wire causing a short circuit.

1 attain my object by means of the constructions hereinafter described and illustrated in the accompanying drawings in which-' Fig. 1 is a verticahsection of the heater;

"Fig. 2 an elevation of part of the heatlng element shown in Fig. 1 and at right angles thereto;

Fig. 3 a side elevation of. a support section:-

Fig. 4: a side elevation of the latter at right angles thereto;

Fig. 5 a plan view of the latter support;

Fig. 6 a side elevation of a modified form of a section; and

.Fig. 7 a plan view of the latter.

In the drawings like numerals of reference indicate corresponding parts in the different figures.

The water jacket of the heater includes the outer shell 1 and the inner shell 2. With the water jacketcommunicates the inlet pipe 3 and theoutlet pipe 4. These shells are connected together at their lower ends so that the inner shell is' open at its lower end for the insertion of the heating element. This heating element includes cylindrical resistance Wire support sections 5 of refractory insulating material adapted to be insorted within the inner shell 2 and to carry suitable resistance wiring. On the periphcry of each support section is formed a helical rib 6 on which the resistance wiring is supported as hereinafter described.

The lower end of the lower support section 5 rests on and is set into the upper end of an end piece 7 of refractory insulating material, in which are secured bolts 8forming electric terminals. This end piece is detachably held in position in any suitable manner at the lower end of the water jacket so that the heating element may be easil removed from or inserted-in the inner shel of the jacket. The preferable arrangement of supporting the end piece 7 is as follows. The outer shell l is provided with an outwardly extending flange 9 and the inner shell 2 with an outwardly-extending flange 10 adapted to be connected with the flange 9 by means of a ring 11 which lies under the flange l0 and is bolted to the flange 9. The end piece 7 is detachably connected with the ring 11 in any suitable manner.

The winding of the resistance wiring is preferably arranged to give a three heat effeet, that is twoindependent windings 12 and 13 are employed, each connected at its lower end to a suitable terminal 8. These windings at their upper end are connected by means of the connecting wires 14 to a conductor 15 formed as a rod fitted in holes extending longitudinally of the support sections 5. At its upper end this rod has suitable nuts 16 threaded thereon adapted to clamp the connecting wires 14:. This conductor extends through a suitable hole in the end piece 7 and at its lower end is provided with the nuts 17 so that it forms a terminal for the third wire from a switch 18 which will be of the usual three heat type and suitably connected with the source of energy.

Referring to Figs. 1 to 5 of the drawings it will be noted thateach support section 5 comprises a hub and two independent ribs 6 and 20 formed thereon. These ribs are formed as portions of two helices and the ends of each rib are substantially diametrically opposite each other and in alinement in an axial plane with the ends of the adjacent rib so that the ribs on each section form in effect a half revolution of-a double thread. To form the sections of similar shape each rib projects substantially half the'thickness of the rib past each end of the hub of each section. With this arrangement it will readily be seen that two separate ooves for the resistance windings will be t irmed by the ribs when the sections are superimposed on one another. It will also be noted that each coiled resistance winding maybe easily placed in position against an axially directed surface of its supporting rib.

The common construction of resistance winding supports is to mold open grooves therein to receive the windings, this method necessitates the use of suitable means to revent an end of a broken resistance win ing from springing out and touching the water jacket. A perforated insulating sleeve is generally used for this purpose which is costly to manufacture and to assemble. To

prevent broken windings touching the water jacket; thus making a short circuit, I form axially extending lugs 21 on the ribs 6 and 20. 0 permit free radiation the lugs are spaced apart on the ribs and are preferably of less height than the width of the grooves formed by the ribs 6 and 20 on adjacent sections.

To prevent lateral displacement of the support sections 5 the hub of each section is rovided with a recess 22 in one end and a boss 23 on its opposite end, the boss being adapted to be received in the recess 22 of the opposite end of an adjacent section so that the sections may be properly fitted into one another. To ensure correct alinement of the sections the recess is preferably provided with a notch 24 and the boss with a lateral projection 25, the notch being adapted to receive the projection formed on an adjacent section.

The method of assembling the heating element is as follows. The lower ends of the resistance windings 12 and 13 are led through holes in the end piece 7 to the terminals 8. The rod 15 is received in the end piece and a support section 5 is disposed thereon, the lower end of the latter being set into the upper end of the end piece which is provided with a recess and a notch to receive the boss 23 and the projection 25 on the support section. The windings 12 and 13 are now placed in position on top of the ribs 6 and 20 respectively and the lugs 21 on the ribs retain the portions of the windings in position. A second section 5 is then positioned on top of the first section whereby the lower ends of the helical ribs 6 and 20 on the second section are in juxtaposition to the upper ends of the helical ribs 20 and 6 respectively of the first section. The ribs on both of the sections forming in effect a complete revolution of a double thread whereby the windings on the ribs of the first section are now covered by the ribs on'the second section, but the upper surface of each of the ribs on'the second section is ex osed. The resistance windings are then p aced in position behind the lugs 21 on the helical ribs of the second section 5. It will readily be seen that any number of support sections 5 may be added to obtain the desired capacity. The upper ends 14 of the windings are then connected to the conductor rod 15 as hereinbefore described. Preferably the upper section at least, is provided with openings 28- to receive and lead the ends 14 to the rod 15. This arrangement permits sections of an independent heating element to be arranged on the rod 15 as hereinafter described.

In Figs. 6 and 7 I show a modified form of support section having one helical rib formed thereon, of course, with this type of section only one resistance winding is used and the rib will form in effect a complete revolution of a single thread. The rib being adapted to aline with the ribs of adjacent sections to form a helical groove for the resistance wire.

Each section is preferably provided with holes 27 which may be alined to provide passages for lead wires in the event of an independent heating element being placed on the upper supporting section as disclosed in my prion patent hereinbefore referred to.

It is obvious that various changes may be made in the details of construction without-departing from the spirit of my invention.

What I claim as my invention is 1. A support of insulating material for an electric heating element comprising a hub and a helical rib formed on its periphe for supporting a resistance wire, said rib Pirming not more than a complete turn about the hub so that the heating element may be axially laid in position against an axially directed surface of the rib.

2. A support of insulating material for an electric heating element comprising a hub and a plurality of helical ribs formed on its periphery for supporting separate resistance wires of a heating element, each of the ribs forming a portion of a turn about the hub so that each resistance wire may be axially laid in .position against an axially directed surface of its supporting rib.

3. A support constructed as set forth in claim 1 in which the rib is provided with integral means for retaining the resistance wire in position.

4. A section for a sectional resistance support comprising a hub and a helical rib formed on the hub, said rib forming not more than one complete turn about the hub and having its axially directed surfaces exposed and adapted to aline with the ribs of adjacent support sections to form a helical groove for a resistance wire.

5. A section for a sectional resistance support comprising a hub and a plurality of helical ribs formed on the hub for supporting separate resistance wires, each of the port for a heating element including a hubhaving one of its ends provided with a boss and having a recess formed in its opposite end, the recess being adapted to receive a boss formed on an adjacent section to prevent their lateral displacement. I

7. A section for a sectional resistance support constructed as set forth in claim 6 in which a notch is formed in the recess and the boss is provided with a projection, the notch being adapted to receive a projection formed on the boss of an adjacent section to ensure correct alinement of the sections.

8. A section for a sectional resistance support comprising a hub and a helical rib formed on the hub, said rib having its ends substantially in alinement in an axial plane and projecting substantiallv half the thickness of the rib past each end of the hub.

9. A sectional resistance support formed 0i a plurality of sections, each section comprising a hub having a rib formed on its periphery for supporting a resistance wire;

. and means integrally formed on said rib for retaining the resistance Wire in position.

Signed at Toronto Can, this 23rd day of March, 1921.

FREDERICK W. MOFFAT. 

